Hydrocracking catalysts for vacuum gas oil &amp; de-metalized oil blend

ABSTRACT

This invention relates to a catalyst and a process for treating heavy hydrocarbons using the catalyst. The catalyst is useful for treating heavy hydrocarbons, de-metallize oil (DMO) and is particularly useful in VGO/DMO hydrocarbon blend. It is also useful for DAO. The catalyst acts to catalytically convert the VGO/DMO blend to shorter-chain valuable hydrocarbon products. The catalyst includes a catalytic support material, a catalytic metal impregnated upon the catalytic support material, and a promoter metal on the catalytic support material to enhance catalytic conversion. The combination of the catalytic support material with catalytic metal and promoter metal is operable to catalytically convert VGO/DMO into hydrocarbon products having shorter carbon chains.

RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional PatentApplication Ser. No. 60/639,909 filed on Dec. 29, 2004, which isincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to the field of catalytic treatment ofheavy hydrocarbons to produce desirable hydrocarbon products, inparticular, a novel catalyst operable to catalytically treatde-metallized oil (DMO) and Vacuum Gas Oil (VGO) Blend.

2. Description of the Prior Art

The flexibility of hydrocracking as a process for refining petroleum hasresulted in its phenomenal growth during the past 15 years. Throughcatalytic treatment, feedstocks can be converted to lower boiling ormore desirable products. Hydrocarbon feedstocks suitable for suchtreatment range from residue to naphtha. Products include such widelydiverse materials such as gasoline, kerosene, middle distillates,lubricating oils, fuel oils, and various chemicals.

Commercial hydrocracking is typically carried out in a single stagereactor or in a two-stage reactor with the stages in series. Numeroushydrocracking catalysts have been explored to treat varioushydrocarbons, to reduce undesirable side effects of the catalytictreatment and/or to extend the life of the catalyst. Development hasalso led to catalysts suitable for severe operating conditions. Effortsfor cost effectiveness are ongoing. The choice of catalysts and of theparticular process scheme will depend on many factors such as feedproperties, desired products properties, size of the hydrocracking unit,and various other economic considerations.

While hydrocracking has been investigated in the past for the purpose ofhydrocracking medium and heavy vacuum gas oil (VGO), there is a need toaddress heavier and different hydrocarbons such as de-asphalted oil(DAO) or de-metallized oil (DMO) to convert this into suitable productfor gasoline lines, jet fuels and diesel oils according to geographicaland seasonal variations in demand. LPG and lubricating bases would alsobe desirable products. A catalyst would be advantageous that is capableof handling large hydrocarbon molecules and heavy poly-aromaticmolecules, in particular, DMO. A catalyst that can process VGO/DMO feedblend would be particularly advantageous. As it is notable that theworld market is tending toward heavier hydrocarbons, a catalyst suitablefor such heavy hydrocarbons would be advantageous.

SUMMARY OF THE INVENTION

The current invention includes a catalyst for and a process forhydrotreating/hydrocracking heavy hydrocarbons. The catalyst isparticularly useful for treating de-metallized oil (DMO) and isparticularly useful in VGO/DMO hydrocarbon blend. The catalyst acts tocatalytically convert the VGO/DMO blend to shorter-chain valuablehydrocarbon products. The catalyst includes a catalytic supportmaterial, a catalytic metal impregnated upon the catalytic supportmaterial, and a promoter metal on the catalytic support material toenhance catalytic conversion. The combination of the catalytic supportmaterial with catalytic metal and promoter metal is operable tocatalytically convert VGO/DMO into hydrocarbon products having shortercarbon chains.

In a preferred embodiment, the catalytic metal component includesmolybdenum and the promoter metal includes nickel.

Regarding the catalytic support materials, a particularly preferredcatalytic support material includes MCM-41 mesoporous material.γ-alumina was used as binder for all catalyst prepared in this research.The amount of γ-alumina used was around 70% of the total catalystsupport for the test runs. In a particularly preferred embodiment, theUSY zeolite is in an absence of γ-zeolite.

In another preferred embodiment, the catalytic support material isβ-zeolite. In another preferred embodiment, the catalytic supportmaterial is USY zeolite. In yet another preferred embodiment, thecatalytic support material is amorphous silica alumina, also called ASA.ASA has a non-uniform structure with low acidity and high surface area.The non-uniform structure tends to create acidic sites that are notavailable to large molecules, which leads to inferior performance of ASAalone as compared to MCM-41 or a combination of MCM-41 with ASA.Similarly, the USY and β-zeolite supports suffer from drawbacks relatedto the microporous nature of the supports which makes the catalyst lessefficient for large molecules since it is diffusion limited. Thesesupports used alone tend to plug rapidly, thereby deactivating thecatalyst. However, the MCM-41 support material overcomes these flaws. Ina preferred embodiment, the catalytic support material is solely ultrastable Y zeolite, MCM41 mesoporous material, β-zeolite, amorphous silicaalumina or combinations thereof. A particularly preferred embodimentincludes a single catalytic support material that is substantially allMCM-41. This material is mesoporous that is well-structured and hasuniform morphology with high surface area. It also has low acidity ascompared to beta and USY support materials. The invention includes theuse of proper support material and a balance between acidic and metallicfunction with the proper distribution of metals throughout the supportmaterial. This is accomplished through the very well-structuredmorphology features of MCM-41 support material, which contains bothacidic and metallic site that are accessible to the large hydrocarbonmolecules found in VGO and DMO. For this reason, high conversion isachieved. Advantageously the lower acidity of MCM-41 as compared toother support materials drives conversion toward selectivity towards middistillates and limits the production of undesirable light gases.

In a preferred embodiment of the invention, the catalytic metal is in asulfide form. For example, molybdenum in the form of molybdenum sulfideis preferred.

In a preferred embodiment, promoter metals include solely nickel.

The catalyst of the invention is particularly useful for VGO/DMOhydrocarbon blend contains at least 10% DMO by volume. Test runs havebeen made for VGO/DMO hydrocarbon blend contains at least 15% DMO byvolume.

Impregnation of the catalytic metal and the promoter metal onto thecatalytic support is accomplished through methods known in the art, suchas co-impregnation method. The process of catalytically converting aheavy hydrocarbon containing de-metallized oil includes the steps ofintroducing the heavy hydrocarbon containing de-metallized oil into areactor stage and introducing the catalyst into the reactor stage. Thecatalyst introduced into the reactor stage includes the catalyticsupport material, the catalytic metal impregnated upon the catalyticsupport material, and the promoter metal on the catalytic supportmaterial to enhance catalytic conversion. The catalytic support materialwith catalytic metal and promoter metal operate to catalytically convertat least a portion of the de-metallized oil into hydrocarbon productshaving shorter carbon chains.

The process reaches and maintains a pre-defined temperature in thereactor operable to achieve conversion. In a preferred embodiment, thepre-defined temperature is at least 390 degrees C. In a moreparticularly preferred embodiment, the pre-defined temperature is atleast 400 degrees C.

In a preferred embodiment, a majority of the pores of the catalystsupport are located within 20 to 50 Angstrom (Å) and the catalystsupport has a large surface area as measured through pore sizedistribution. Table 1 shows examples of preferred embodiments. TABLE 1Prepared Catalysts Textual Characteristics Average BET Surface Area PoreVolume Pore Diameter Sample (m²/g) (cm³/g) (A⁰) NiMo-ASA 186 0.33 36NiMo-MCM-41 324 0.40 25 NiMo-β 313 0.41 26 NiMo-USY 300 0.35 23

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features, advantages and objects of theinvention, as well as others that will become apparent, may beunderstood in more detail, more particular description of the inventionbriefly summarized above may be had by reference to the embodimentthereof which is illustrated in the appended drawings, which form a partof this specification. It is to be noted, however, that the drawingsillustrate only a preferred embodiment of the invention and is thereforenot to be considered limiting of the invention's scope as it may admitto other equally effective embodiments.

FIG. 1 depicts a schematic of a preferred embodiment of the process withthe catalyst of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Several catalysts were prepared using nickel (Ni)/molybdenum (Mo) metalsloadings along with the four different support materials identifiedabove. The four catalyst formulations created in this manner werecharacterized using gas sorption analyzer, temperature programmedreduction (TPR) and temperature programmed de-sorption (TPD). Moreover,the catalyst formulations were tested in a batch reactor and comparedagainst a commercial catalyst. The outcome of this work showed that theformulation including MCM-41 catalyst support, resulting in NiMo-MCM-41,has performed better than the commercial catalyst on heavy hydrocarbons,in particular, VGO/DMO blends. NiMo-MCM-41 showed higherhydrodesulfurization (HDS) and hydrogenation activities. In addition, ithad higher conversion and higher diesel yield than commercial catalyst.

Most of the hydrocracking catalysts of commercial interest are dualfunctional in nature, consisting of both a hydrogenation-dehydrogenationcomponent and an acidic support. The reactions catalyzed by theindividual components are quite different. In specific catalysts, therelative strengths of the two components can be varied. The reactionsoccurring and the products formed are influenced by the balance betweenthese two components. TABLE 2 Acidity for all prepared catalystsCatalyst Acidity (mmol/g) Peak Temperature (° C.) NiMo-MCM-41 0.33 264NiMo-ASA 0.50 252 NiMo-β 0.56 233 NiMo-USY 0.59 238

Table 2 shows the TPD of ammonia for all of the prepared hydrocrackingcatalysts. The acidity of the prepared catalysts ranges from 0.33 mmol/g(NiMo-MCM-41) to 0.59 mmol/g (NiMo-USY). The lower acidity ofNiMo-MCM-41 catalyst is expected since MCM-41 is a silica based materialand has low amount of alumina. Therefore, NiMo-MCM-41 catalyst has loweramount of γ-alumina than the other prepared catalysts.

The catalytic metal, such as molybdenum, and the promoter metal, such asnickel, provide the hydrogenation-dehydrogenation functions. As noted,this is preferably in the sulfide form. Other group VIA and group VIIIAmetals are useful as promoter metal and catalytic metal. These metalscatalyze the hydrogenation of the feedstock, making it more reactive forcracking and heteroatom removal, as well as reducing the coking rate.They also initiate the cracking by forming a reactive olefinintermediate via dehydrogenation.

Since hydrocracking of industrial feedstocks is to be carried inpresence of hydrogen sulfide and organic sulfur compounds, it ispreferred that the metal site be in a metal sulfide form of the VIAgroup promoted by a nickel or cobalt sulfide.

The reactions that occur during the hydrocracking process take threemajor routes. First, non-catalytic thermal cleavage of C-C bonds viahydrocarbon radicals, with hydrogen addition (hydropyrolysis). Second,monofunctional C-C bond cleavage with hydrogen addition overhydrogenation components consisting of metals, oxides or sulfides(hydrogenolysis). Third, bifunctional C-C bond cleavage with hydrogenaddition over bifunctional catalysts consisting of a hydrogenationcomponent dispersed on a porous, acidic support. In addition to theabove reactions, there are other reactions that take place during thehydrocracking process. These can include hydrodesulfurization,hydrodeintrofication, hydrodeoxigenation, olefin hydrogenation andpartial aromatic hydrogenation. TABLE 3 Experimental Design CatalystSystems Com- NiMo- NiMo- NiMo- NiMo- mercial MCM-41 USY β ASA CatalystPreparation γ-alumina binder, 70 70 70 70 wt % Support, wt % 30 30 30 30NiO, wt % 2.5 2.5 2.5 2.5 MoO3, wt % 12 12 12 12 Ni, wt % 2 2 2 2 Mo, wt% 8 8 8 8 Atomic Ratio 0.2 0.2 0.2 0.2 Catalyst Characterization SurfaceArea, 324 300 313 186 m²/g Pore Vol., cm³/g 0.4 0.35 0.41 0.33 PoreSize, 25 23 26 36 Angstrom Acidity, 0.33 0.59 0.56 0.5 mmol/gm CatalystEvaluation Batch Reactor — — No. of Runs 5 1 1 1 1 Temperatures, 410 410410 410 410 deg. C. Pressures, kg/cm² 150 150 150 150 150 Feed weight, g100 100 100 100 100 Catalyst weight, g 3 3 3 3 3

The commercial catalyst that was used for comparison is DHC-8 fromUniversal Oil Products (UOP) Company. γ-alumina was used as binder forall catalyst prepared in this test shown above. The amount of γ-aluminaused was 70% of the total catalyst support. TABLE 4 Feedstock DefinitionVGO/DMO Feedstock Properties VGO DMO 85%/15% Specific Gravity 0.92-0.930.96-0.97 0.93-0.94 Total Nitrogen, wt ppm 700-900 1300-2100 1100-1200Total Sulfur, wt % 2-3   3-3.5 2.6-2.8 ASTM Distillation, D2887 5%, ° C.279 402 50%, max ° C. 472 596 495 90%, max ° C. 543 678 615 Ni + V wt.ppm <1  8.0-13.5 2-3

TABLE 5 Tested catalysts conversion for 800-900° F. cut and 900-1050° F.cut ¹Conversion % NiMo- NiMo- NiMo- NiMo- Cut Range, ° F. CommercialMCM-41 β ASA USY 800-900 13.37 19.23 17.57 15.78 15.04 900-1050 35.2936.33 32.74 34.56 35.69 Overall 27.01 29.97 27.01 27.47 27.89

Among the four catalyst formulations described above that areencompassed within the invention, NiMo-MCM-41 catalyst had the lowestacidity and the highest surface area. This is attributed to the factthat MCM-41 is a silica-based material and has low amounts of alumina.This is one of the advantages of MCM-41 being mesoporous and having lowacidity. The mesoporous feature along with the lower acidity ofNiMo-MCM41 catalyst promotes the highest conversion and the lowest gasmake.

While the invention has been shown or described in only some of itsforms, it should be apparent to those skilled in the art that it is notso limited, but is susceptible to various changes without departing fromthe scope of the invention.

1. A catalyst for treating VGO/DMO hydrocarbon blend to catalyticallyconvert the VGO/DMO blend to shorter-chain valuable hydrocarbonproducts, the catalyst comprising: a catalytic support materialcomprising MCM-41 mesoporous material, a catalytic metal impregnatedupon the catalytic support material, and, a promoter metal on thecatalytic support material to enhance catalytic conversion, thecatalytic support material with catalytic metal and promoter metaloperable to catalytically convert VGO/DMO into hydrocarbon productshaving shorter carbon chains.
 2. The catalyst of claim 1 wherein thecatalytic metal component is molybdenum and the promoter metal isnickel.
 3. The catalyst of claim 2 wherein the catalytic supportmaterial is solely MCM-41 mesoporous material.
 4. The catalyst of claim2 wherein substantially all of the nickel is in the form of nickelsulfide.
 5. The catalyst of claim 1 wherein the catalytic metalcomponent is selected from the group consisting of molybdenum, tungstenand combinations thereof, and wherein the promoter metal is selectedfrom a group consisting of nickel, cobalt and combinations thereof. 6.The catalyst of claim 1 wherein the VGO/DMO hydrocarbon blend containsat least 10% DMO by volume.
 7. The catalyst of claim 1 wherein theVGO/DMO hydrocarbon blend contains at least 15% DMO by volume.
 8. Thecatalyst of claim 1 wherein the catalytic metal and the promoter metalare impregnated upon the catalytic support through co-impregnation. 9.The catalyst of claim 1 wherein the catalytic metal and the promotermetal are impregnated upon the catalytic support through successiveimpregnation.
 10. The process of catalytically converting a heavyhydrocarbon containing de-metallized oil comprising the steps of:introducing the heavy hydrocarbon containing de-metallized oil into areactor stage, introducing the catalyst into the reactor stage, thecatalyst comprising: a catalytic support material comprising MCM-41mesoporous material, a catalytic metal impregnated upon the catalyticsupport material, and, a promoter metal on the catalytic supportmaterial to enhance catalytic conversion, the catalytic support materialwith catalytic metal and promoter metal operable to catalyticallyconvert at least a portion of the de-metallized oil into hydrocarbonproducts having shorter carbon chains.
 11. The process of claim 10wherein the catalytic metal component is molybdenum and the promotermetal is nickel.
 12. The catalyst of claim 11 wherein the catalyticsupport material includes ultra stable Y zeolite.
 13. The process ofclaim 11 wherein the catalytic support material is solely MCM-41mesoporous material.
 14. The process of claim 11 wherein the catalyticsupport material includes β-zeolite.
 15. The process of claim 11 whereinthe catalytic support material includes amorphous silica alumina. 16.The process of claim 11 wherein the catalytic support material isselected from the group consisting of ultra stable Y zeolite, MCM-41mesoporous material, β-zeolite, amorphous silica alumina, andcombinations thereof.
 17. The process of claim 11 wherein at least aportion of the nickel is in the form of nickel sulfide.
 18. The processof claim 11 wherein the catalytic metal component is selected from thegroup consisting of nickel, cobalt and combinations thereof, and whereinthe promoter metal is selected from a group consisting of molybdenum,tungsten and combinations thereof.
 19. The process of claim 11 whereinthe VGO/DMO hydrocarbon blend contains at least 10% DMO by volume. 20.The process of claim 11 wherein the VGO/DMO hydrocarbon blend containsat least 15% DMO by volume.
 21. The process of claim 18 wherein at leasta portion of the nickel is in the form of nickel sulfide.
 22. Theprocess of claim 18 wherein at least a portion of the cobalt is in theform of cobalt sulfide.
 23. The process of claim 10 wherein thecatalytic metal and the promoter metal are impregnated upon thecatalytic support through co-impregnation.
 24. The process of claim 10wherein the catalytic metal and the promoter metal are impregnated uponthe catalytic support through successive impregnation.
 25. The processof claim 10 further comprising the step of maintaining a pre-definedtemperature in the reactor.
 26. The process of claim 25 wherein thepre-defined temperature is at least 390 degrees C.
 27. The process ofclaim 25 wherein the pre-defined temperature is at least 400 degrees C.